Distribution of programs over wires



v 1,666,154 J. F. TOOMEY DISTRIBUTION OF PROGRAMS OVER WIRES April 17,1928. I

Filed July 12.1924

IN VEN TOR JZ 150W Patented Apr. 17, 1928 I z ,1; a

TELEGRAPH COMPANY, A CORPORATION or NEW" YORK.

"DISTRIBUTIONYVOIF rRoeRAMs OVER WIRES,

' Application filed Julyllz,1924..SriaiNo.725,G43. f" v This inventionrelates to the distribution of programs over More lines, andmoreparticularly to an amplifying arrangement to:

be vused in connection with such systems.

In a system for thedistribution of music,

news, entertainment, etc, over wire trans mission lines, it 1s customaryto establlsh a connection from the studio or other point at .which theprogram originates. over a trunk to a central ofiice from Whl Ch' branchtrunks extend to points in local areas, such as I apartment houses Ateach apartment house or other'local area branches extend from eachdistributingtrunkto thereceiving equipment located at the subscriberspremises. Atveach distributing point, such, for example, as the centralstation, or the p I p from battery, over the switch 13,"-thr0,ugh

local distributing point, such as an'apartment house, it is desirabletoprovide amtributing trunk or subscribers branch.

' rAt such distributing points ,it-is not-21 up its armature in serieswith the high re ways convenient to have an attendant on Y duty-tomaintain the amplifying equipment.

may be .substituted forthe'regular equip ment without interruptingtheservice there by enabling a trouble man to rectity the.

ditficulty at his convenience.

-The invention ,will now bev moreiully :un-L

derstood from the following description wheniread in connection Wlthtllfl accom I panyingdrawing, thefigure of which illustratesan'amplifying arrangement embodying the principles of the invention.

Referring to the-drawing, T may be taken torepresent a trunkextendingfrom astud-io' to a distributing P011113 or a trunk extendingfrom a centraltdistributing point to a local distributing point such asan apartnent house- Atthe apartment house, am-

plifying equipment. is provided comprising two amplifying stages, thefirst stage comprising preferably a ,single tube amplifier and thesecond stage comprisingpreterably a push-pull amplifier. Atube isPIOVldGCl as the normal amplifier for the first vstage,

' and an auxiliary tube 10": is adapted to be switched in the circuit inthe event that the tube 10;should fail. 1 Similarly, tubes 11 and 12,normally function as. the amplifiers V thatthe switching of anauxiliary tube will be under, the control of a marginal relayin we Icircuit with the filament of the regular tube, thev relay being soarranged that it-will ,au vtomatica lly disconnect theregular" tube andthe 24 volt ba y;

relay 19 to point 20. 'From-pointf20 the cir- I v 'of th e second stagepushepull combination, auxiliary tubes 11. and 12 being provided JOHN F.rooMEY, on NEW YoRig-iv. Y nssxenoRao AMERICAN TELEPHONE Ann" to besubstituted in the case of failure ofthe regular tubes. The circuits"are so arranged substitute an auxiliary tube in case the filament ofthe regular tube should burnout. v

Further -detailsof the apparatus willfnow i be clear from'the'description the opera tion, which is asfollowsr I 1 l/Vhenever itis desired to place the'eircuit' in condition for transmission, .a'sw'itch13 will be closedlthereby completing a circuit;

marginalrelay l l, over the ring side'of the trunk T, through the highresistance windl,

ingot the relay 15,, andfback over the tip 'side of thetrunkT; toground. The relay 15 is energizedover the circuit above traced. 1 Therelay. 14 being marginal doesnot pull contact, throughthewindingoifl'relay- G to V thereby-energizing the, 1 I s5 p relay G. Relay inturn "completes a cit cuit' from the 24 volt,battery over itsgfrontcontact, through impedance. coil 16 and're- I sistan'ce'l'? to the point18, thence in parallel over the left hand back contact of marginal t andouter right-hand back contact ofrela'y' relay19, through the filamentofjtubefl2 19 to point 20, and from ,thei point "18 through theenergizing wind ng of marginal ouit extends to. point121and'then'ce inparallel :over'the' outer right-handback Contact ,i

of] marginal relay 22, through the filament and from the point2l throughthe energizof tube 11, and "overfthe left-hand back con- 1' tact ofmarginalrelay 22 to'the point 23',

23. From point the circuitextendsjtopoint 24 and. thencein' parallelover the left hand back contact of marginal relay} 25, through thefilament of the tube 10, outer right-hand *backcontact'of relay 25topoint;

10c ing winding of marginal relay 22, to point put circuits 7 of theamplifiers. therefore flows from the plate of the first traced that thecircuit extends through the filament of each normal tube in parallelwith the operating winding of the marginal relay. Suiiicient currentflows through the filaments of each of the normal tubes 10, 11 and 12 sothat the filaments glow and each filament shunts the energizing windingof the corresponding relay to such an extent that an insuliicient amountof current flows through the marginal relay to cause its energization.

As soon as I the filaments of the tubes begin to glow, the space currentflows in the outstage tube 10, through the primary winding oftransformer 28, through the winding of the relay I to the 350 voltsource of space current, thereby energizing the relay 1. Similarly,current flows in parallel from the plates of the tubes 11 and 12 of thesecond stage amplifier to the midpoint of the primary winding of thetransformer 29 and thence through the winding of the relay L to the 350volt plate source. Relays I and L, upon being energized, complete acircuit from ground over the front contact of relay L and over the frontcontact of relay l through the left-hand winding of relay H to the 24cvolt battery thereby energizing relay H and looking it up through itsrighthand winding and over-its right-hand front contact to ground overthe front contact of relay 15. A relay '30 is connected in the leadwhich extends to the 350 volt plate source so that as soon as'currentflows to the plate circuits of the amplifying equipment the relay 30 isenergized and completes a shunt circuit through the low resistanceWinding of the relay 15, said shunt circuit extending over the backcontact of the relay F. The closing of the low resistance shunt circuitincreases the current flow over the trunk T thereby energizing relay 1 1which completes a circuit for the lamp31 to indicate that the circuit isin operative condition. Transmission may now take place in the regularmanner.

In case'the350 open the low resistance shunt winding of the relay 15,thereby 'causing'the marginal relay let to be deenergized. When thearmature of the relay 14 falls OK, the lamp 31 will be extinguished,thereby indicating that there is trouble on the circuit. In the eventthe tube 10 should fail by reason of burning out its filament, thecurrent through the left-hand winding of the marginal relay 25 will beincreased owing to the opening of the shunt path about said winding.Marginal relay 24: will thereby be energized and will be locked up overa circuit from the 2 1 volt battery, over the front contact of relay Gr,through the right-hand locking Current the marginal volt power sourceshouldv fail, the relay 30 will be deenergized and winding of relay 25and over its inner righthand front contact and through the lefthandwinding of relay F to ground over restoring key li. At its outer frontcontacts relayzf) substitutes the filament circuit of the auxiliary tube10 for the filament circuit of the tube 10 so'that the tube 10 at oncefunctions, and transmission may proceed as before- 'lhe relay F, uponbeing energized, opens the low resistance shunt winding of the relay 15to cause the signal lamp at 31 to be extinguished thereby indicatingtrouble upon the circuit, so that an attendant may substitute a new tubefor the tube 10. Upon replacing the tube 10, the

attendant opens the key K thereby releasing the relay i and unlockingthe marginal relay 25 which is restored to normal and agaln connects thefilament'of the tube 10' in circuit, softhatthe tube 10 now functions asthe amplifier. The releasing of the relay F again closes thecircuitthrouglr the low resistance shunt winding of the relay 1'5 andcauses the signal lamp 31 to again glow. A. similar action takes placein case the filaments of either of the tubes 11 or 12 should burn out.

1n the event that plate current should fail to flow through the relay Ifor any reason, its armature in falling off will complete a circuit fromground, over the front contact of relay L and back contact of relay l,frontv contact of lock up relay H and through the winding of the relay Fto the 2s volt battery. Similarly, if the space currents should fail toflow through the winding of the relay L, a circuit will be completedfrom ground, over the back contact of relay L, front contact of relay H,and through the right-hand winding of relay F to battery. In every casethe relay F will be energized thereby opening the low resistance shuntof the relay 15 and causing the lamp 81 to indicate trouble on the line.When the circuit is no longer to be used for transmission, the switch 13will be opened thereby 'deenergizing marginal relay ll and relay 15.Relay 15 opens the locking circuit of relay H and also opens the circuitof relay G so that all of the apparatus is restored to normal. a

lit will be obvious that the general prm ciples herein disclosed-may beembodied in many organizations widely difierent from those illustratedwithout departing from the spirit of the inventionas defined in thefollowing claims.

What is claim-ed'is: I i 1. In a transmission circuit, an amplifiercomprising a normal vacuum tube and circuits therefor, a spare vacuumtube, a mar ginal relay supplied with current from the filament currentsupply-circuit of said normal vacuum tube, and means controlled by saidrelay whereby when said filament burns cuits therefor, a sparevacuum'tub'e, a current supply circuit for energizing the fila- .ment ofsaid normal tube, a marginal relay connected 1n parallel with. saidfilament,-sa1d'marg1nal relay remaining deenergized while current flowsthroughsaid filament and adapted to be energized'when the filament burnsout, and means controlled by said marginal relay for switching saidspare tube into theamplifier circuit in place of the normal tube. v

3. In a transmission circuit, a multi-staget spare tube'therefor.

fication, a marginal relay connected in shunt with the filament of eachnormal tube, said plifier comprising a normal tube and circuitsthere'for for each stage of am'plifica tion, aspare tube for eachstage of ampIi-H marginal relay being deenergized as long as current,fiowsthrough the filament but being energized when the -filament-burnsout, and switching means controlled by each' marginal relay fordisconnecting the corresponding normal tube and .substituting'the Intestimony whereof, I have signedmy July, 1924. I JOHN F. TO'OMEY.

[a name to thisspecificationthis 11th day of

